//============================================================================
//
//  This file is part of GPSTk, the GPS Toolkit.
//
//  The GPSTk is free software; you can redistribute it and/or modify
//  it under the terms of the GNU Lesser General Public License as published
//  by the Free Software Foundation; either version 3.0 of the License, or
//  any later version.
//
//  The GPSTk is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU Lesser General Public License for more details.
//
//  You should have received a copy of the GNU Lesser General Public
//  License along with GPSTk; if not, write to the Free Software Foundation,
//  Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110, USA
//
//  Copyright 2004, The University of Texas at Austin
//  Dagoberto Salazar - gAGE ( http://www.gage.es ). 2007, 2008, 2009, 2011
//
//============================================================================

//============================================================================
//
//This software developed by Applied Research Laboratories at the University of
//Texas at Austin, under contract to an agency or agencies within the U.S.
//Department of Defense. The U.S. Government retains all rights to use,
//duplicate, distribute, disclose, or release this software.
//
//Pursuant to DoD Directive 523024
//
// DISTRIBUTION STATEMENT A: This software has been approved for public
//                           release, distribution is unlimited.
//
//=============================================================================

/**
 * @file BasicModel.hpp
 * This is a class to compute the basic parts of a GNSS model, i.e.:
 * Geometric distance, relativity correction, satellite position and
 * velocity at transmission time, satellite elevation and azimuth, etc.
 */

#ifndef GPSTK_BASICMODEL_HPP
#define GPSTK_BASICMODEL_HPP

#include "../gpstk/ProcessingClass.hpp"
#include "../gpstk/EphemerisRange.hpp"
#include  "../gpstk/EngEphemeris.hpp"
#include  "../gpstk/XvtStore.hpp"
#include  "../gpstk/GPSEphemerisStore.hpp"

namespace gpstk
{
/** @addtogroup GPSsolutions */
//@{

/** This is a class to compute the basic parts of a GNSS model, like
 *  geometric distance, relativity correction, satellite position and
 *  velocity at transmission time, satellite elevation and azimuth, etc.
 *
 * This class is intended to be used with GNSS Data Structures (GDS).
 * It is a more modular alternative to classes such as ModelObs
 * and ModelObsFixedStation.
 *
 * A typical way to use this class follows:
 *
 * @code
 *      // Input observation file stream
 *   RinexObsStream rin("ebre0300.02o");
 *
 *      // Load the precise ephemeris file
 *   SP3EphemerisStore sp3Eph;
 *   sp3Eph.loadFile("igs11513.sp3");
 *
 *      // Reference position of receiver station
 *   Position nominalPos(4833520.2269, 41537.00768, 4147461.489);
 *
 *      // Some more code and definitions here...
 *
 *   gnssRinex gRin;  // GNSS data structure for fixed station data
 *
 *      // Set defaults of models. A typical C1-based modeling is used
 *   BasicModel model( nominalPos, sp3Eph );
 *
 *   while(rin >> gRin)
 *   {
 *
 *         // Apply the model on the GDS
 *      gRin >> model;
 *   }
 *
 * @endcode
 *
 * The "BasicModel" object will visit every satellite in
 * the GNSS data structure that is "gRin" and will try to compute
 * its model: Geometric distance, relativity delay, satellite position
 * at transmission time, satellite elevation and azimuth, etc.
 *
 * When used with the ">>" operator, this class returns the same
 * incoming data structure with the extra data inserted along their
 * corresponding satellites. Be warned that if a given satellite does
 * not have ephemeris information, it will be summarily deleted
 * from the data structure.
 *
 * @sa ModelObs.hpp and ModelObsFixedStation.hpp for classes carrying
 * out a more complete model.
 *
 */
class BasicModel : public ProcessingClass
{
public:

    /// Default constructor. Observable C1 will be used for computations
    /// and satellites with elevation less than 10 degrees will be
    /// deleted.
    BasicModel()
        : minElev(10.0), pDefaultEphemeris(NULL),
          defaultObservable(TypeID::C1), useTGD(false)
    {
        setInitialRxPosition();
    };


    /** Explicit constructor taking as input reference
     *  station coordinates.
     *
     * Those coordinates may be Cartesian (X, Y, Z in meters) or Geodetic
     * (Latitude, Longitude, Altitude), but defaults to Cartesian.
     *
     * Also, a pointer to GeoidModel may be specified, but default is
     * NULL (in which case WGS84 values will be used).
     *
     * @param aRx   first coordinate [ X(m), or latitude (degrees N) ]
     * @param bRx   second coordinate [ Y(m), or longitude (degrees E) ]
     * @param cRx   third coordinate [ Z, height above ellipsoid or
     *              radius, in meters ]
     * @param s     coordinate system (default is Cartesian, may be set
     *              to Geodetic).
     * @param ell   pointer to EllipsoidModel.
     * @param frame Reference frame associated with this position.
     */
    BasicModel( const double& aRx,
                const double& bRx,
                const double& cRx,
                Position::CoordinateSystem s = Position::Cartesian,
                EllipsoidModel *ell = NULL,
                ReferenceFrame frame = ReferenceFrame::Unknown );


    /// Explicit constructor, taking as input a Position object
    /// containing reference station coordinates.
    BasicModel(const Position& RxCoordinates);


    /** Explicit constructor, taking as input reference station
     *  coordinates, ephemeris to be used and whether TGD will
     *  be computed or not.
     *
     * @param RxCoordinates Reference station coordinates.
     * @param dEphemeris    EphemerisStore object to be used by default.
     * @param dObservable   Observable type to be used by default.
     * @param applyTGD      Whether or not C1 observable will be
     *                      corrected from TGD effect.
     *
     */
    BasicModel( const Position& RxCoordinates,
                XvtStore<SatID>& dEphemeris,
                const TypeID& dObservable = TypeID::C1,
                const bool& applyTGD = false );


    /** Returns a satTypeValueMap object, adding the new data generated
     *  when calling a modeling object.
     *
     * @param time      Epoch.
     * @param gData     Data object holding the data.
     */
    virtual satTypeValueMap& Process( const CommonTime& time,
                                      satTypeValueMap& gData )
    throw(ProcessingException);


    /** Returns a gnnsSatTypeValue object, adding the new data generated
     *  when calling a modeling object.
     *
     * @param gData    Data object holding the data.
     */
    virtual gnssSatTypeValue& Process(gnssSatTypeValue& gData)
    throw(ProcessingException)
    {
        Process(gData.header.epoch, gData.body);
        return gData;
    };


    /** Returns a gnnsRinex object, adding the new data generated when
     *  calling a modeling object.
     *
     * @param gData    Data object holding the data.
     */
    virtual gnssRinex& Process(gnssRinex& gData)
    throw(ProcessingException)
    {
        Process(gData.header.epoch, gData.body);
        return gData;
    };


    /// Method to get satellite elevation cut-off angle. By default, it
    /// is set to 10 degrees.
    virtual double getMinElev() const
    {
        return minElev;
    };


    /// Method to set satellite elevation cut-off angle. By default, it
    /// is set to 10 degrees.
    virtual BasicModel& setMinElev(double newElevation)
    {
        minElev = newElevation;
        return (*this);
    };


    /// Method to get the default observable for computations.
    virtual TypeID getDefaultObservable() const
    {
        return defaultObservable;
    };


    /** Method to set the default observable for computations.
     *
     * @param type      TypeID object to be used by default
     */
    virtual BasicModel& setDefaultObservable(const TypeID& type)
    {
        defaultObservable = type;
        return (*this);
    };


    /// Method to get a pointer to the default XvtStore<SatID> to be used
    /// with GNSS data structures.
    virtual XvtStore<SatID>* getDefaultEphemeris() const
    {
        return pDefaultEphemeris;
    };


    /** Method to set the default XvtStore<SatID> to be used with GNSS
     *  data structures.
     *
     * @param ephem     XvtStore<SatID> object to be used by default
     */
    virtual BasicModel& setDefaultEphemeris(XvtStore<SatID>& ephem)
    {
        pDefaultEphemeris = &ephem;
        return (*this);
    };


    /// Either estimated or "a priori" position of receiver
    Position rxPos;


    /// Returns a string identifying this object.
    virtual std::string getClassName(void) const;


    /// Destructor.
    virtual ~BasicModel() {};


protected:


    /// The elevation cut-off angle for accepted satellites.
    /// By default it is set to 10 degrees.
    double minElev;


    /// Pointer to default XvtStore<SatID> object when working with GNSS
    /// data structures.
    XvtStore<SatID>* pDefaultEphemeris;


    /// Default observable to be used when fed with GNSS data structures.
    TypeID defaultObservable;


    /// Whether the TGD effect will be applied to C1 observable or not.
    bool useTGD;


    /** Method to set the initial (a priori) position of receiver.
     * @return
     *  0 if OK
     *  -1 if problems arose
     */
    virtual int setInitialRxPosition( const double& aRx,
                                      const double& bRx,
                                      const double& cRx,
                                      Position::CoordinateSystem s = Position::Cartesian,
                                      EllipsoidModel *ell = NULL,
                                      ReferenceFrame frame = ReferenceFrame::Unknown );


    /// Method to set the initial (a priori) position of receiver.
    virtual int setInitialRxPosition(const Position& RxCoordinates);


    /// Method to set the initial (a priori) position of receiver.
    virtual int setInitialRxPosition();


    /// Method to get TGD corrections.
    virtual double getTGDCorrections( CommonTime Tr,
                                      const XvtStore<SatID>& Eph,
                                      SatID sat )
    throw();


}; // End of class 'BasicModel'

//@}

}  // End of namespace gpstk

#endif   // GPSTK_BASICMODEL_HPP
